JPH0253029A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain oriented films which have excellent durability and can well orient a ferroelectric liquid crystal by forming at least one of the oriented films of a film formed by irradiating the film of a polymer essentially consisting of an acrylonitrile polymer with electron rays and/or UV rays. CONSTITUTION:Transparent electrodes 2a, 2b and the oriented films 3a, 3b are respectively laminated in this order on transparent substrates 1a, 2b to constitute transparent electrode substrates 5, 6. The transparent electrode substrates 5, 6 are respectively so disposed that the oriented films 3a, 3b face each other and the liquid crystal 4 is sealed therebetween. At least either of the oriented films 3a, 3b is formed by irradiating the film essentially consisting of the acrylonitrile polymer with the electron rays and/or UV rays. The moisture resistance and liquid crystal resistance of the acrylonitrile polymer are improved by subjecting the film to the treatment of irradiating the same with the electron rays and/or UV rays. The liquid crystal display element having the oriented films which are highly durable and well orient the ferroelectric liquid crystal is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to liquid crystal display elements. More specifically, the present invention relates to a liquid crystal display element having an alignment film that is excellent in durability and allows ferroelectric liquid crystal to be aligned well.

[Technical Background of the Invention and Prior Art] Liquid crystal display elements conventionally used in watches, computers, word processors, etc. have, as their basic structure, two transparent electrode substrates with an alignment film provided on the transparent electrodes. Usually, the structure is such that the alignment film is placed on the inside and the liquid crystal is sealed between them. Generally, in a liquid crystal display element, it is necessary to align the liquid crystals in a certain direction, that is, to align them, so in the above liquid crystal display element, an alignment film is provided to align the liquid crystal molecules.

The mainstream of such liquid crystal display elements is display in a leistid nematic (TN) mode in which nematic liquid crystal has a twisted structure. However, this TN type liquid crystal display element has a slow response speed, currently limited to 20 milliseconds, which is a major problem when used in television panels etc. that require high-speed response. It has become.

In contrast, recently, ferroelectric liquid crystals with high-speed response are expected to open up a new field of displays.
being researched. In a display element using this ferroelectric liquid crystal material, it is important to align the liquid crystal molecules in a certain preferred direction parallel to the substrate surface. However, the smectic liquid crystal having a chiral smectic phase used in this ferroelectric liquid crystal display element generally has poor alignment stability compared to the general nematic liquid crystal mentioned above, and the liquid crystal molecules are aligned parallel to the substrate surface. It is difficult to arrange them in a certain preferred direction. For this reason, many proposals have been made to better align ferroelectric liquid crystals, but none of them can be said to have satisfactorily solved this problem.

For example, one method for aligning ferroelectric liquid crystals is to apply a strong magnetic field and use file stress, but these methods are not practical in terms of production processes, and alignment from spacer edges has been proposed ( r Nature J July 1983 issue, pages 36-46, rt Buto-Kuss (OPT
RONIC9) J September 19B3 issue, pages 64-70
(see page), but the region in which -like orientation can be achieved is also narrow, from the edge to 1100JL.

It is still insufficient in terms of practical application.

On the other hand, there is a method of obliquely depositing silicon oxide (Sin) (Japanese Patent Publication No. 54-12067), which is used to control the alignment of conventional nematic liquid crystals and cholesteric liquid crystals, and a method of rubbing with a specific cloth after applying polyimide, etc. In the case of ferroelectric liquid crystals, the alignment film provided by this method does not provide sufficient alignment.Also, the method of depositing a polyimide resin material in vacuum and then polymerizing it by heating (Special EIJI Edict 61- No. 138924) has also been proposed, but in this method of forming a polymer film forming material and heat-treating it, the processing temperature of the heat treatment is high, and other components of the liquid crystal display element, such as color filters and transparent It may have an adverse effect on the circuit board, etc.

Polyimide film formed by glow discharge
219029) as an alignment film enables low-temperature processing, but since the organic and organometallic compounds to be polymerized must be vaporized, there are restrictions on the selection of polymerization materials, and Depending on the situation, it may be necessary to vaporize under extremely harsh conditions. Furthermore, even if the alignment film obtained in this manner is used, depending on the liquid crystal, it may not always be aligned sufficiently, resulting in a problem of a decrease in contrast.

JP-A-62-227123 discloses a ferroelectric liquid crystal display element using polyacrylonitrile for one alignment film and using polyetheramide, polyamic acid, polyimide, or silane for the other. There is.

Although this liquid crystal display element has relatively well-oriented ferroelectric liquid crystal, it has problems in moisture resistance and liquid crystal resistance because polyacrylonitrile is not a crosslinked molecule a'i5.

[Summary of the Invention] An object of the present invention is to provide a liquid crystal display element having excellent durability and having an alignment film in which ferroelectric liquid crystal can be aligned well.

The above object is a liquid crystal display element according to the present invention, in which two transparent electrode substrates each having an alignment film provided on a transparent electrode are arranged with the alignment film inside, and a liquid crystal is sealed between them; This can be achieved by a liquid crystal display element characterized in that at least one of the alignment films is a film formed by irradiating a polymer film containing an acrylonitrile-based polymer as a main component with electron beams and/or ultraviolet rays.

The inventor of the present invention has proposed that after the conventional process of applying an alignment film-forming material containing an acrylonitrile-based polymer as a main component and forming a film by performing heat treatment, etc., the film is further coated with an electron beam and/or an ultraviolet ray. The inventors have discovered that the moisture resistance and liquid crystal resistance of acrylonitrile-based polymers can be significantly improved by adding a treatment of irradiation with irradiation, leading to the present invention. The reason why the moisture resistance and liquid crystal resistance of acrylonitrile polymers are greatly improved by irradiation with electron beams and/or ultraviolet rays is that a crosslinking reaction occurs within the acrylonitrile polymer molecules and a crosslinked structure is formed within one molecule. This is thought to be due to the

Preferred embodiments of the present invention are listed below.

(1) A liquid crystal display element, wherein the acrylonitrile polymer is polyacrylonitrile.

(2) A liquid crystal display element, wherein the liquid crystal is a ferroelectric liquid crystal.

(3) The irradiation dose of the electron beam is 0.01 to 100 Mr
A liquid crystal display element characterized by being an ad.

(4) The irradiation dose of the electron beam is 0.1 to 80 Mrad.
A liquid crystal display element characterized by:

(5) A liquid crystal display element characterized in that the irradiation time of the ultraviolet rays is 10 seconds to 3 hours.

(6) A liquid crystal display element characterized in that the irradiation time of the ultraviolet rays is 1 minute to 60 minutes.

[Configuration of the Invention] The configuration of the liquid crystal display element of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an example of the liquid crystal display element of the present invention. Transparent electrodes 2a, 2b, on transparent substrates 1a, lb,
The alignment films 3a and 3b are stacked in this order to constitute a transparent electrode substrate 5.6. Transparent electrode substrate 5.6
In the liquid crystal display element of the present invention, in which the alignment films 3a and 3b are arranged to face each other, and the liquid crystal 4 is sealed between them, at least one of the alignment films 113a and 3b is
It is characterized in that it is a film formed by irradiating a film containing an acrylonitrile polymer as a main component with electron beams and/or ultraviolet rays.

The liquid crystal display element of the present invention is not limited to the one shown in FIG. 1, but can be made in any manner that is used for ordinary liquid crystal display elements, such as providing an electrical insulating layer, using a spacer, or providing a polarizing plate. It is. In particular, it is preferable to use a spacer to ensure the gap between both alignment films (i.e., the thickness of the liquid crystal layer).The spacer may be made of glass fiber, glass fist beads, plastic beads, alumina, silica, etc. Metal oxide particles are used. The particle size of the spacer varies depending on the liquid crystal used, alignment film material, cell gap setting, metal oxide used, etc., but is generally from 1.21 Lm to 6 Lm.

The transparent substrate, the transparent electrode, and the liquid crystal used in the liquid crystal display element of the present invention can all be the known ones that have been conventionally used in liquid crystal display elements.

For example, as a transparent substrate, in addition to glass such as float glass with good smoothness, polyester such as polyethylene terephthalate and polybutylene terephthalate, epoxy resin, phenol resin, polyimide, polycarbonate, polysulfone, polyether sulfone, polyetherimide, acetyl cellulose, polyamino acid ester,
It is formed from heat-resistant resins such as aromatic polyamides, vinyl polymers such as polystyrene, polyacrylic esters, polymethacrylic esters, polyacrylamide, polyethylene, and polypropylene, fluorine-containing resins such as polyvinylidene fluoride, and modified products thereof. Examples include plastic films.

As the transparent electrode, indium oxide (In203),
Tin oxide (Sn02) and! TO (indium O tin oxide) and the like can be mentioned.

The liquid crystal display element of the present invention, even those using TN liquid crystal or STN liquid crystal, has excellent moisture resistance and is effective in obtaining good alignment, but the effects of the present invention are most effectively exhibited in the 1. As the 0 ferroelectric liquid crystal, which is a liquid crystal display element using a ferroelectric liquid crystal, conventionally known ones can be used.

Below, liquid crystals with ferroelectricity are specifically chiral smectic C phase (SmC), H phase (SmH umbrella), and I phase (SmC'').
It is a liquid crystal having a J phase (SmJ㉟), a K phase (SmK・), a G phase (SmG・), or an F phase (SmF fist).

For example, the following molecules are used as ferroelectric liquid crystals.

0 sentence C sentence R CI CH3 l CH3 Or, ON CH3 A specific liquid crystal composition is C5-1o manufactured by Chisso ■
11. C5-1013, C5-1015, ZLI-3488, ZLI-3489 manufactured by Merck, Teikoku Kagaku Sangyo ■
H3-98P, MS-78F (both product names)
These liquid crystals may include, but are not limited to, dimorphic dyes, thinners, and the like that are soluble in the liquid crystal without any problem.

Next, the alignment film, which is a feature of the liquid crystal display element of the present invention, will be described.

The liquid crystal display element of the present invention is characterized in that at least one of the two alignment films is a film formed by irradiating a polymer film containing an acrylonitrile-based polymer as a main component with electron beams and/or ultraviolet rays. do.

This alignment film may be provided directly on the transparent electrode, or may be provided on the transparent electrode with a film having other functions such as an electrically insulating layer.

The acrylonitrile-based polymer used in the present invention is an acrylonitrile homopolymer (ie, an acrylonitrile homopolymer).

Polyacrylonitrile) or a copolymer mainly composed of repeating units derived from acrylonitrile can be used. The content of repeating units derived from acrylonitrile is generally 60 mol% or more, preferably 70 mol% or more.

Examples of substances that form copolymers with repeating units derived from the above-mentioned 7-crylonitrile include (meth)acrylic acid esters, vinyl halides, and styrene.
There are no particular limitations as long as it copolymerizes with acrylonitrile.

The thickness of the alignment film varies depending on the liquid crystal used, but is approximately 200A.
~2000A is preferred.

Next, a method for manufacturing the liquid crystal display element of the present invention will be described.

In order to manufacture the liquid crystal display element of the present invention, at least one of the two alignment films is coated with an alignment film-forming material containing an acrylonitrile-based polymer as a main component, and is formed by heat treatment or the like. After the conventional process, this film is formed by adding a step of irradiating it with electron beams and/or ultraviolet rays.

An example of manufacturing the liquid crystal display element of the present invention will be described below in order.

A coating liquid for an alignment film forming material containing the acrylonitrile polymer as a main component is applied onto a transparent electrode provided on a transparent substrate by a conventional method. In addition to acrylonitrile-based polymers, the coating solution also contains materials that improve the physical properties of the film.
Other polymers, organic metals, etc. may be added as subcomponents for the purpose of increasing adhesion with the substrate or adjusting the viscosity of the coating solution.Also, a crosslinking agent may be added as an auxiliary component. The coating may be applied directly onto the transparent electrode, or an insulating layer may be provided on the transparent electrode and the coating may be applied thereon.

After the transparent electrode substrate provided with the coating film is heat-treated, it is subjected to electron beam and/or ultraviolet ray irradiation treatment, which is a feature of the present invention. These treatments themselves can be carried out using known methods. For example, electron beam irradiation is carried out using a normal electron beam irradiation device (EB?t). , although it varies depending on the size etc.
0.01-100 Mrad is suitable, preferably 0
．． 1 to 80 Mrad. In addition, rare gas discharge tubes such as ultraviolet & IWA irradiation treatment, high pressure mercury lamps, low pressure mercury lamps, metal halide lamps, xenon lamps, (deuterium) hydrogen discharge tubes, etc. can be used as light sources. The irradiation time varies depending on the thickness and width of the film, the wavelength characteristics and output of the light source lamp, etc., but is generally 10 seconds to 3 hours, preferably 1 minute to 60 minutes.

The alignment film treated in this way is made of synthetic materials such as nylon, polyester, and polyacrylonitrile. l,
Rubbed with natural fibers such as cotton and wool.

Manufactured as described above. A pair of transparent electrode substrates each having at least one of them a transparent electrode substrate composed of a transparent substrate, a transparent electrode, and an alignment film are placed facing each other with a liquid crystal sandwiched therebetween, with the alignment film facing inside.

Of course, the liquid crystal display element of the present invention can be provided with structures provided in conventional liquid crystal display elements, such as a polarizing plate, an electrical insulating layer, and a color filter, depending on the purpose of use.

Next, Examples and Comparative Examples of the present invention will be described.

However, the present invention is not limited to this example.

[Example 1] A transparent electrode of indium tin oxide was provided on a glass substrate (thickness 1.1 mm), polyacrylonitrile (manufactured by Aldrich) was applied thereon, and heat treated at 150°C for 1 hour. A film with a thickness of 001 gm was formed. This transparent electrode substrate was set in an electron beam irradiation device and exposed to 2M under a nitrogen stream.
The electron beam was irradiated at a dose of rad. After standing for 24 hours, this film was rubbed three times with a polyester cloth to obtain an alignment film. The same process was repeated to obtain another transparent electrode substrate similar to the above. These two transparent electrode substrates were bonded together with a spacer interposed so that the rubbing directions were parallel to each other, to create a liquid crystal cell with a cell gap of 2ILm. A ferroelectric liquid crystal ZLI-3775 (manufactured by Merck & Co., Ltd.) was injected into this cell, heated to 100°C, and then heated to 4°C.
The mixture was slowly cooled to 0° C. to obtain a liquid crystal display element.

[Comparative Example 1] A liquid crystal display element was manufactured in exactly the same manner as in Example 1, except that electron beam irradiation was not performed.

[Moisture Resistance Test] The liquid crystal display element of Example 1 and the liquid crystal display element of Comparative Example 1 were left for 1000 hours at a temperature of 50° C. and a humidity of 90%, and then observed under crossed Nicols. The results are shown in Table 1.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing an example of the structure of a liquid crystal display element according to the present invention. Observation Results in Table 1 Good alignment was observed, and no blemish was observed in Example 1. Comparative Example 1 Many bleeds were observed. 1a, 1b: Transparent substrates 2a, 2b: Transparent electrodes 3a, 3b: Alignment film 4: f & product 5.6: Transparent electrode substrate Patent applicant Fuji Photo Film Co., Ltd. Representative Patent attorney Yasuo Yanagawa It is clear from the above results. As such, the liquid crystal display element of the present invention is a liquid crystal display element that has excellent durability and has an alignment film that allows ferroelectric liquid crystal to be aligned well.

Claims (1)

[Claims] 1. A liquid crystal display element in which two transparent electrode substrates each having an alignment film provided on a transparent electrode are arranged with the alignment film inside, and a liquid crystal is sealed between them; at least one of the alignment films is 1. A liquid crystal display element characterized in that the film is formed by irradiating a polymer film containing an acrylonitrile-based polymer as a main component with electron beams and/or ultraviolet rays.